There are two rules in science that every researcher soon learns: what you don’t see is as important as what you do see and a paradox means that you are on the edge of learning something amazing. In today’s adventure, Peter and Mary find this out for themselves as they see what darkness lurks in the hearts of galaxies!
Sharing a sunset with friends is always good. As the sun paints the sky with vivid shades of orange, red, and purple (and a flash of green), you can discuss the important stuff, such as what you like best and where you want to live when you get older. But the best part is just being there with your friends, sharing something unique and special. And that’s what Peter and Mary were doing on a particularly clear summer night – just hanging out and being friends.
Of course, for them, some of the answers were already known. They both liked science best of all, and enjoyed doing experiments whenever they could. And they didn’t really care where they lived as long as it was someplace where they could do experiments, though Mary really preferred Houston simply because that was where all of the other astronauts lived. But there were still some questions that they hadn’t answered. And Mary had one for Peter.
“So why did you mother say we should be out here tonight? She isn’t trying to get you out of the house so she can run more simulations, is she?” Peter’s mother was an astronomer who sometimes needed more peace and quiet than a house with a young son could provide, so she would ask Peter to run errands or do experiments outside while she concentrated.
“No, she just said that it was time that I learned some of the deepest, darkest secrets of the universe and told me to be here after sunset. I wonder what we’ll learn?” he mused.
“You’ll discover that just as soon as we get some basics down,” said a cheerful voice behind them; turning around, they saw Peter’s mother holding three small bags. “Come and grab these binoculars!”
As the two each took a bag and opened it to reveal a good but inexpensive pair of binoculars, Peter’s mother continued her explanation.
“We’re going to look into the night sky and see one of the most amazing things ever described,” she said. “But before we do, we need to figure out how to make sure that we are all looking at the same thing. Any ideas on how we could do that?”
“You keep muttering under your breath about ‘right ascension’ and ‘declination’ when you are working on a problem,” Peter replied.
“But I don’t know what those are!” Mary objected.
“Well, neither do I,” Peter admitted. “But it is what she says.”
“When we are in the lab or using a big, expensive telescope, we do use those terms,” Peter’s mother said. “They are a mathematical grid that helps us locate things in the sky, much as latitude and longitude help on the ground. But we don’t drive around using latitude and longitude. Instead, we use street signs and relative directions like ‘turn left after the next block’.”
“So what are the street signs in the sky?” asked Mary.
“The constellations,” replied Peter’s mother. “They tell us which part of the sky to look in. For example, the nearest star to the Sun is…”
“Alpha Centauri!” Peter interrupted.
“Close but no cigar,” his mother said. “It is actually Proxima Centauri; the name ‘Proxima’ means ‘nearest’ and ‘Centauri’ means that it is found in the Centaurus constellation. But Proxima is too dim to be seen with the naked eye and is right next to Alpha, astronomically speaking, so most non-scientists think that they are the same.”
“Why do we call it Alpha Centauri?” Mary asked.
“Ah, that’s like a street number in our sky map,” Peter’s mother replied. “The stars are given a designation based on their apparent brightness – how bright they look from Earth. The brightest star in a constellation is ‘alpha’, the next-brightest is ‘beta’, then ‘gamma’ and so on. Many of the brightest stars also have a name in Arabic -”
“Like Betelgeuse!” Mary said.
“Right, the good old ‘shoulder of the giant’. And we’ve got ‘the follower’ Aldebaran in Taurus or ‘the tail of the hen’ Deneb in Cygnus. But you can’t drive with a street map in your face and you can’t find stars at night using those names until you’ve got a lot more experience. So tonight, we’ll use the old astronomer standby of ‘face East and make a fist’.”
“Huh?” said Peter. “What good will that do?”
“Well, let’s start by facing East,” his mother replied. Humoring her, the two obediently turned to face the opposite direction from where the Sun had gone down.
“Now spread you hand wide and sweep it from East to directly overhead to West,” she commanded. As they did so, Peter’s mother explained, “What you’ve just done is sweep out half of the ecliptic plane; that’s the band where most of the stuff in the Solar System lives. Most of the planets and asteroids and other junk in our Solar System will be found in the band you just described with your hand. So if we ever go looking for planets, that’s where we can look.”
“Neat!” Mary said. “So we can see Jupiter?”
“If it was up tonight, we could,” Peter’s mother said. “But it won’t be up until well after you two go to bed, which is a shame because you could see the moon of Jupiter with your binoculars. We’ll have to try it some night when Jupiter is up earlier. But for tonight, what I want you to to is face East and count three fists to the North and four fists up. When you put a fist at arm’s length, it is always about ten degrees, no matter who or how old you are, so fists are an astronomer’s favorite quick and dirty measuring method. When you get to the position, look at it and tell me what you see.”
“That’s just old Orion’s sword,” Peter said. “There’s nothing special there.”
“I wouldn’t be so sure,” his mother replied. “Look at it again, only use your binoculars.”
The two looked through their binoculars at the sword hanging from Orion’s belt and let out gasps of wonder.
“It’s full of stars!” Mary exclaimed.
“Even better,” Peter’s mother said. “It is full of baby stars and planets; that is a stellar nursery where new solar systems are being born.”
“Wow!” Peter said. “Is the whole sky like this?”
“That’s exactly why I asked you to come out here tonight,” said his mother. “When I was your age, your grandfather brought me out to a field and showed me what you’ve just seen. And then he made a bet with me. He bet me $10 that I couldn’t find a part of the sky without stars.”
“That’s easy,” Mary said. “There’s an empty patch over there!”
“Look at it through the binoculars,” Peter’s mother said.
“Whoa! It has stars!”
“Yes, that’s right. So here’s my challenge to you two – can you fins any part of the sky that has no stars in it when seen through the binoculars?”
“Sure we can!” Peter said.
“I don’t know,” Mary replied. “I thought my patch was dark but it really wasn’t.”
Well, there is only one way to know for sure,” Peter’s mother said. “Do the experiment!”
What do you think will happen? Do the experiment yourself!
For twenty minutes, Peter and Mary searched the sky looking for patches without stars. Time after time they’d get excited about a seemingly empty area only to see it fill with stars when they looked at it through the binoculars. They tried down near the horizon and up near the zenith overhead, but every area had stars. Finally, the two gave in and admitted that the entire sky was filled with stars.
“No matter where we look, there are stars in the sky,” Peter said. “But why don’t we see them?”
“For the same reason that you don’t see a candle from a mile away,” his mother explained. “Stars are just big light sources in the sky. And the farther away they are, the dimmer they get. You can see them with the binoculars because they gather more light and make dim things visible. Telescopes do the same thing; all binoculars are is two telescopes strapped together. As a matter of fact, when the Hubble telescope stared at one place in the sky for five days, it discovered over a thousand galaxies in a patch of the sky that you could cover with your thumb. That means billions of stars and trillions of planets, all out there in the deepness of space.”
“Wow!” Mary said. “But if there are all of those stars out there, then why is the night sky dark?”
Peter’s mother chortled happily.
“You have just discovered Olber’s Paradox!” she said. “Back in 1823, an astronomer by the name of Olber made famous a problem that had puzzled astronomers since Kepler’s day: ‘if the universe is infinite and there are stars wherever we look, then why is the night sky dark?'”
“So what is the answer?” demanded Peter.
“I’ve given you enough hints to know the answer,” his mother replied.
“You said “if the universe is infinite-‘” Mary started.
“That’s it!” Peter exclaimed. “The universe isn’t infinite!”
“Got it in one!” his mother said. “The solution to the paradox is that the universe isn’t infinite. As a matter of fact, it is only about 13.8 billion years old – remember that infinite implies age as well as width – and so there isn’t enough space for an infinite number of stars nor has there been enough time an infinite number of stars to have formed.”
“Gosh!” Mary said.
“Gosh indeed,” replied Peter’s mother. “And now that we’ve solved the paradox, let’s just look at the stars.”
Turning their binoculars skyward, that’s what they did.
Today’s factismal: Mosquitoes pollinate many types of flower including goldenrod and orchids.
The mosquito is the “little fly” (the literal translation of its name from Portuguese) that everyone loves to hate. Annoying, whining, disease vectors, they are better known for the few times that they suck blood than for the majority of times that they feast on plant nectar. But it is true; the male mosquito only eats the nectar of certain plants while the female will only indulge in a bit of vampirism when she’s ready to lay eggs; otherwise, she’s a confirmed nectar-eater, too. Among the plants that mosquitoes like to visit are the goldenrod, orchids, and chocolate.
So if mosquitoes feed on plants, why do they also attack people (and other animals) for blood? Simply put, they do it for the sake of their children. In order for a mosquitoes eggs to hatch properly, they need to contain a specialized protein that is commonly found in the blood of animals. Scientists still aren’t sure which protein it is (some like to point to those with threonine), but they know that without that protein and the iron in blood, mosquito eggs won’t hatch.
Mosquitoes find that protein by quite literally following their nose. They can smell the difference between different animals and hone in those with more of what they want. In a recent experiment using identical and non-identical twins, mosquitoes were found to attack one identical twin about as often as the other but would frequently attack one non-identical twin twice as often as the other, demonstrating the mosquitoes ability to smell out the best source of goodies for their eggs. Other studies have shown mosquitoes are more attracted to people who are heavy breathers (which spreads the scent farther), those who haven’t bathed recently (which gives a lot more odor), and folks with type O blood.
Though mosquitoes are just doing what they need to do to provide for their children, they do a lot of damage along the way. They can carry diseases such as Dengue fever, malaria, yellow fever, and elephantitis; during the construction of the Panama Canal, an estimated 20,000 people died from mosquito-borne diseases. Sadly, that toll continues today, all over the world. But some places are doing something about it. Places like Baltimore, which has started a citizen science program to identify places where mosquitoes are thickest so that they can find the breeding areas and drain them. TO learn more, buzz over to:
Today’s Factismal: There were nearly 4,000 earthquakes today.
There was just a Mw 7.5 earthquake off of Papua New Guinea today. And there was a Mw 7.8 temblor in Nepal last week. And they aren’t alone; over the past week, there were nearly 30,000 earthquakes. But don’t worry. There were that many earthquakes the week before, too. And there will be that many next week as well. The fact is that every day there are 4,000 earthquakes and every year there are nearly one and a half million earthquakes across the globe.
These earthquakes happen because the Earth is very slowly cooling down. Radioactive decay in the mantle (the thick solid section between the liquid outer core and the crust) and solidification of the outer core create heat inside the Earth. That heat, plus a little “fossil heat” from the Earth’s formation, creates convection in the mantle. And the motion of the mantle drives motion of the Earth’s crust, breaking it into large rigid sections called plates. As the plates collide to form mountain ranges or scrape alongside in transform zones, they release energy as earthquakes.
And what a lot of energy they release! A magnitude 2.5 earthquake will give off enough energy to power a home for 14 hours, and there are nearly 1,300,000 earthquakes that large every year. Even better, the energy goes up much faster than the magnitude. A magnitude 4 earthquake gives off enough energy to power a home for 1.6 years. Fortunately, the number of earthquakes also decreases faster than the magnitude; there are only about 13,000 magnitude 4 earthquakes every year.
And that relationship between energy and magnitude is why we can’t prevent a large earthquake by triggering a lot of small ones. It takes about 33 magnitude 7 earthquakes to release the same energy as one magnitude 8. So let’s suppose that you live in a place where you get a magnitude 8 about once every hundred years. You’d need to have a magnitude 7 every three years to release the strain. Or you could do it with a magnitude 6 every month. Or a magnitude 5 every day. Or a magnitude 4 every 45 minutes. Or a magnitude 3 every minute. Obviously, this is not a good idea.
What is a good idea is keeping up with the most recent earthquakes using either the Rapid Earthquake Viewer or the USGS Earthquake Monitor. And please contribute to science by telling the USGS if you felt the earth move!
Gathering data for an experiment often takes a lot of patience and work. But the results can be astonishing, as Peter and Mary discover in this week’s Secret Science Society adventure.
Peter was bored. It was Saturday morning and he was stuck in the backyard with nothing to do for at least an hour because his mother had told him to go outside. She had very firm ideas about fresh air and exercise and didn’t think that they could be found in front of a TV or computer screen, especially not on a weekend. So he kicked his soccer ball back and forth, halfheartedly practicing headers and fancy footwork. With his mind on the fun TV programs he was missing, he wasn’t paying much attention to what he was doing and so with a little too much oomph from one kick, his soccer ball went sailing over the fence and into the neighbor’s backyard.
If he had been practicing on the other side of the yard, his ball would have gone into old Mr. Thomson’s yard. Mr. Thomson still hadn’t forgiven him for the time Peter had accidentally crushed a rose bush while trying to walk along the fence like a tightrope walker, though Peter thought buying him a new rose bush and having the pull the thorns from the old one out of his skin would have been punishment enough. But Mr. Thomson disagreed and would have looked on the arrival of Peter’s soccer ball as another opportunity to extract vengeance. Fortunately for Peter, he’d been playing on the other side of the yard.
And his neighbor on that side was Mary. She was one of his best friends and they shared a love of science and experiments that meant he’d be able to retrieve the soccer ball without any of the difficulties that Mr. Thomson would have caused. Or at least, that’s what he thought. As Peter ran out of his backyard and over to Mary’s, he heard a familiar feminine voice crying out “dratsab!”
As he slowly opened the gate, Peter saw Mary staring at a broken stick surrounded by white gravel. On the gravel were several black rocks and his soccer ball. Mary stood glaring at the ball with the stick in one hand and a black rock in the other.
“Sorry!” Peter said as he opened the gate. “It got away from me.”
“Well, why don’t you watch what you’re doing?” Mary snapped. “You’ve just ruined an experiment that I’ve been working on all year long!”
“I’m sorry,” Peter repeated, staring down at the mysterious collection of black rocks. “Can I help you fix it?”
“I don’t know,” Mary replied. “We can put the old measurements back easily enough. But I’ll have to get another stick exactly as long as this one and I don’t know if I can.”
“What measurements?” Peter asked. “And why does the stick need to be exactly that long?”
“I’m making an analemma for my science far project this year,” Mary said. “Those black rocks show the measurements that I’ve already made. I was on my way out to make another one when your soccer ball came through and ruined everything.”
“What’s an analemma? What are you measuring?”
“I’m measuring the length and placement of the shadow that the stick makes – made,” she corrected herself with another glare at Peter. “It shows how the Sun appears to move through the sky.”
“I still don’t get it,” Peter said.
“Let’s go talk to your mom; she’s the one who explained it to me,” Mary said.
The two gathered up the pieces of the broken stick and the soccer ball before they quickly left the rocks and headed over to Peter’s house. As they came in the kitchen door, Peter’s mother called out from the study.
“Peter! I told you to go outside and get some fresh air. Ten minutes is barely enough time to take a breath!”
“Sorry, Mom!” he replied as Mary held up the stick from her experiment. “I accidentally broke Mary’s analemma and she told me you could tell me what it is so I can help her fix it.”
“Ah, light dawns. Well, we’ll just have to find another stick.”
“Can we do that?” Mary asked.
“Sure, as long as the stick is about the same length and put in the same place as the old one, it should be OK. The Greeks did this with broken sundials so you are fine.”
“But what is an analemma?” Peter interrupted. “Why won’t you tell me how it works?”
“There’s no big secret to it,” his mother replied. “But the best way to explain it is with an experiment. Hand me your soccer ball.”
Mystified, Peter gave his soccer ball to his mother. She rooted in her desk and pulled out a thumbtack and some tape. She taped the thumbtack to the soccer ball with the point facing outward; the thumbtack was about one-quarter of the way down the soccer ball. Next, she took the shade off of a lamp on her desk. Placing the lamp in the middle of the room, she motioned to Peter and Mary to come over.
“This is our model of the Sun and Earth,” she said as she pointed to the lamp and ball. “First let’s figure out what is what. When I turn the ball on its axis, that makes a day, right?” As the pair nodded, she continued. “So when the lamp is directly facing the side with the thumbtack, what time is it?”
“Noon!” Mary promptly replied.
“Right! Now look at the shadow the thumbtack makes. See how it it facing in one direction and has a certain length? What do you think will happen if I take the soccer ball over to the other side of the lamp?”
“This is the part that took me a while to get,” Mary admitted.
“I don’t know,” Peter said. “It will probably cast another shadow just like this one.”
“Let’s find out,” his mother replied.
What do you think will happen? Do the experiment and find out!
Peter’s mother moved to the other side of the room and again turned the ball to face the lamp.
“Hey!” Peter said. “The shadow’s different! You must have twisted the ball somehow.”
“Close but no cigar,” his mother replied. “I didn’t do anything; Mama Nature did. You see, the Earth is spinning but the spin axis is not straight up and down. Instead, it is about twenty-two degrees off. As a result, the Sun appears to move higher and lower in the sky as the season’s change. The Greeks noticed this from the shadows that their sundials made and gave the pattern a name – analemma or ‘pedestal of the sundial’. Here, you try it. Hold the soccer ball so that the bottom seam is parallel to the ground and then put it at about half of halfway to perpendicular and see what happens to the shadow.”
Taking the soccer ball from his mother, Peter tilted it back and forth slowly and watched the shadow cast by the thumbtack get longer and shorter with the tilt.
“OK, so the tilt causes the shadow to change,” he said. “Big deal.”
“You are right,” Mary said. “It is a big deal.”
“It is that tilt that causes the Earth’s seasons,” his mother replied. “When it is winter in the Northern hemisphere, the Earth is closer to the Sun. You’d think that we’d be warm but because the Earth is tilted only a little of the sunlight hits the Northern hemisphere while a lot more hits the Southern hemisphere. As a result, we’re cold while they get hot. And then it reverses in the summer; we’re tilted so that we get more direct sunlight and so we get warm while they get cold.”
“That’s what I was doing with my experiment,” Mary said. “I was tracking the length of the shadow and the temperature. I wanted to show that the temperature was due to the Sun’s apparent position.”
“Sorry,” Peter said once more.
“But what Mary was doing is just the most obvious part of the experiment,” his mother said. “It turns out that things get even more interesting. What happens if the tilt decreases?”
“Then we get about the same amount of sunlight in both winter and summer,” Peter said.
“And that means that the temperatures should be about the same!” Mary exclaimed. “And if we had more tilt, then we’d get even colder winters and warmer summers.”
“And that is the root of Milankovitch cycles,” Peter’s mother said. “The Earth’s tilt slowly changes through time. Add in a few other changes in our orbit that happen naturally and we have periods with lots of long, cold winters and other periods with shorter, warmer ones. Those long cold winters are perfect for making snow which then piles up and creates…”
“An ice age!” Mary said.
“Right,” said Peter’s mother. “We’ve used various proxies such as tree rings to help us discover how long and cold the winters were in the past and we’ve discovered that Milankovitch was really on to something. That’s why climatologists include his work in their studies. But speaking of discovering, I think that you’ll find Peter has some wooden dowels about the right length in his workshop in the garage.”
“You’re right!” he said. “Let’s go get one and put your experiment back together!”
“OK,” Mary said. “But let’s hurry – I make the measurement at the same time every day and it is almost that time!”
The two young scientists ran out of the room, headed for a new stick, another measurement, and all of the fresh air and sunshine that a mother could ask for.
Today’s Factismal: May is National Zombie Awareness Month..
If you think that zombies are just found in the movies, then think again. There are real live zombies out there, and they may be in your neighborhood. But what is a zombie, really? And how did it get that way?
Put simply, to a biologist a zombie is any animal that no longer acts under its own control but is instead controlled by a parasite. The best known example of this in the animal kingdom is the poor leafcutter ant. In forests across Brazil, Thailand, and Africa, leafcutter ants are regularly attacked by a fungus known as Ophiocordyceps unilateralis (“Single fruiting body poking out of the head”, which describes how it reproduces). This disease primarily preys on leafcutter ants that make their homes in masses of bound together leaves, far above the ground.
As soon as an ant has this disease, it begins to twitch and thrash until it either falls out of the nest or is thrown by colony members who don’t want to catch it themselves. The infected ant finds a leaf, grabs on with its mandibles, and has its brain eaten by the fungus. As soon as the fungus has nibbled all of the goodies to be found in this ant, it then cracks open the ant’s head and grows a stalk with a fruiting body on the tip. The fruiting body releases spores and the whole cycle starts all over again.
And it isn’t just funguses that can cause this behavior. There are bacteria, wasps, and even flies that do this. Most ominous of those is the fly Apocephalus borealis, which turns honeybees into zombies. This “scuttle fly” is much smaller than a honeybee, but is capable of infecting dozens of honeybees with its eggs. The eggs hatch into larvae that then eat their way to the bee’s brain and drive it insane. (Bwah-hah-hah!) The bee then does stupid things, like flying at night or in the rain, which spreads the larvae further than they could go on their own. The larvae finally finish off the bee and eat their way out of the poor dead bee.
This is a severe problem for people because we rely on honeybees to fertilize many of the crops that we eat. Without honeybees, we’d be very hungry indeed. If you’d like to help spot zombees and track the spread of the zombee apocalypse, then join the ZombeeWatch: